Out of curiosity I googled the issue. As mentioned already, that board requires a BIOS update to work with that CPU.
Excerpt from 1 article on toms hardware:
Quick post to everyone here having the same issue, i have the P8Z68-V PRO/GEN3 mobo and was having the same issue with my i5-3570k CPU. This is my first build so i dont have any older parts and didn't feel like bringing it to PC repair shop. A week later i finally found it was incompatibility issues with Ivy Bridge (after thinking it was power supply or mobo messing up) since my mobo was running on 0301. Here's what to do:
Head over to Asus support website here:
Download the 3202 rom and extract the file onto a FAT32 USB device
Don't put the USB device in the mobo just yet as it wouldn't let me reach the BIOS, only tell me that there's no OS. Once you do get to the BIOS (after a few failed boot i'm guessing) insert the USB Key (be extra careful not to fry anything since MOBO is running and go to:
Advance -> Tools -> EZ Flash Utility (or something like that)
It will install the update. I just did it and i got 5 successfull boots/resets in a row without any issue. It should be worth noting that i did it with a barebread setup, i only had Mobo, CPU, CPU Fan, GPU and Power supply while doing it.
Hope this helps a few people, this was an incredibly frustrating week, especially with Diablo 3 being released next week. I'll put everything in the case and install Windows, i'll update later if anything goes wrong or fine.
PS: Sorry for my english.
Link to the article: